1. Field of the Invention
This invention relates to a mixing head for mixing fluids and more particularly to a mixing head for mixing fluids which set and harden after being mixed.
2. The Prior Art
A major disadvantage of present mixing heads for mixing fluids which set and harden upon mixing arises because of the differences in pressures at which the various fluids are injected into the mixing chamber. To inject the fluids into the mixing head, the fluids may be pumped through injection lines by means of a positive drive pump similar to the one disclosed in U.S. Pat. No. 3,838,948 issued Oct. 1, 1974 to McCorvey, the disclosure of which is incorporated herein by reference. The relative amount of each fluid injected into the mixing chamber is determined by the positive drive of the pump. The pressure at which each fluid is injected depends upon the viscosity of the fluid, the size of the orifice through which the fluid is pumped, and the amount of fluid pumped. With fluids of different viscosities, and with different amounts of each fluid being pumped, the fluids enter the mixing chamber at different pressures. A fluid that enters the chamber under a high pressure tends to back up into the lower pressure fluid injection line. The resulting mixing of the two fluids in the injection line contaminates the line and sometimes causes hardening in the line. Accordingly, it is an object of this invention to provide a mixing head where the possibility of fluids backing up into another fluid injection line is eliminated.
Another object is to provide a mixing head wherein the pressure from one line is not exerted on another line.
The texture of the mixed fluid is determined by the relative slug of fluid size (as contrasted with the relative volumetric amount) of the fluids to be mixed. With present systems it is difficult to control the slug size of the fluids to be mixed, and thus the texture of the finished product cannot easily be adjusted. It is another object of this invention to provide a mixing head which has means for controllably varying the size of the slugs of fluid to be mixed so the product texture can be controlled.
These and other objects and features of advantage of this invention will become apparent from the drawings, the claims, and detailed description which follows.